1. Field of the Invention
The present invention relates to a device for detecting state of approach of an object such as an obstacle.
2. Prior Art
Heretofore, a device for detecting an object which is used, for example, as an obstacle detecting device for detecting an obstacle during running of an automobile comprises a transmitter for transmitting an electromagnetic wave or a ultrasonic wave having directivity and a receiver for receiving the wave which has been reflected from the object, thereby detecting the object, such as obstacle.
Such a convntional device requires the use of the transmitter and the receiver, so that it is complicated in construction. Furthermore it employs a wave having directivity, so that it tends to provide an insensible area at close range.